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https://issues.apache.org/activemq/browse/AMQ-2184?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=52698#action_52698
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Rob Davies commented on AMQ-2184:
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Hi Norbert - we don't do patches to the 5.1 branch - is this an issue with 5.3
(trunk currently) ? If not can you close it ?
> Messages keep hanging in JDBCStore without delivery to client
> -------------------------------------------------------------
>
> Key: AMQ-2184
> URL: https://issues.apache.org/activemq/browse/AMQ-2184
> Project: ActiveMQ
> Issue Type: Bug
> Components: Broker
> Affects Versions: 5.1.0, 5.2.0
> Environment: OS: Linux version 2.6.26-amd64-85 (r...@etch64) (gcc
> version 4.1.2 20061115 (prerelease) (Debian 4.1.1-21))
> ActiveMQ: 5.1.0
> 1 Broker, 12 JBoss's with round about 20 consumers and 20 Producers on 7
> JDBC persistant queues
> Clients use transacted consumers.
> Reporter: Norbert Pfistner
> Assignee: Rob Davies
> Priority: Trivial
> Fix For: 5.3.0
>
> Attachments: NonBrowsableMessaagesJConsole.jpg,
> NonBrowsableQueueEntries.jpg, NonBrowsableQueueEntries.txt,
> NonBrowsableQueueEntryList.jpg
>
>
> We currently suffer from hanging messages in the JDBC persistant storage in
> our production environment.
> Occasionally (once in a day or week) a few Messages (most time 1 or 2,
> sometimes more) seems to stuck in the DB Table activemq_msg without being
> delivered even once to a consumer. They are never deliverd to a consumer
> until the broker is rebooted. Strange enough new messages produced into the
> same queue with those stuck messages are delivered to the consumers as
> normal. It simply looks like the borker is blind about the stuck messages.
> Our system depends on processing every message, so missing even one of them
> is realy a big problem in production.
> Everything seems to be fine: No warnings, errors or even debug logging gives
> any hint about a problem.
> Unfortunately we can't debug the broker 'cuse it's our production
> environment. Our Testing envirenment is not capable to reproduce the problem
> (actually it's only one Machine with a Broker and a signle jaboss running a
> small number of producers/clients).
> Our messaging characteristics show moderate producers and slow consumers.
> The count of simultanous messages is moderate (about 300-1000). Actually the
> producers have hot phases generating bulks of Messages followed by phases of
> long inactivity. The consumers are slow related to the producers but always
> keep within an hour or two. We do not experience any memory problems.
> Because this bug may be related to
> https://issues.apache.org/activemq/browse/AMQ-1918, I had a look at the code
> around the StoreCursors and stumbled apon a strange code fragment called when
> removing entries.
> The suspicous code is found in
> org.apache.activemq.broker.region.cursors.AbstractStoreCursor.remove() in
> 5.1.0, 5.2 .0 and 5.3.0:
> public final synchronized void remove() {
> size--;
> if (size==0 && isStarted() && cacheEnabled) {
> cacheEnabled=true;
> }
> }
> As far as i can see, the if statement ist actually a NOP, 'cause it will not
> modify cacheEnabled in any case.
> Maybe this causes some strange effects when using the StoreCursor's derived
> from this class..
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